Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/103—Selection of coding mode or of prediction mode
  • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/127—Prioritisation of hardware or computational resources
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/136—Incoming video signal characteristics or properties
  • H04N19/137—Motion inside a coding unit, e.g. average field, frame or block difference
  • H04N19/139—Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/172—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a picture, frame or field
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/189—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/189—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding
  • H04N19/196—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the adaptation method, adaptation tool or adaptation type used for the adaptive coding being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/42—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/44—Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
  • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
  • H04N19/51—Motion estimation or motion compensation
  • H04N19/513—Processing of motion vectors
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
  • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
  • H04N19/51—Motion estimation or motion compensation
  • H04N19/573—Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction

Definitions

• This disclosure relates generally to field of data processing, and more particularly to video encoding and decoding.
• Uncompressed digital video can consist of a series of pictures, each picture having a spatial dimension of, for example, 1920 x 1080 luminance samples and associated chrominance samples.
• the series of pictures can have a fixed or variable picture rate (informally also known as frame rate), of, for example 60 pictures per second or 60 Hz.
• Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video at 8 bit per sample (1920x1080 luminance sample resolution at 60 Hz frame rate) requires close to 1.5 Gbit/s bandwidth. An hour of such video requires more than 600 GByte of storage space.
• Video coding and decoding can be the reduction of redundancy in the input video signal, through compression. Compression can help reducing aforementioned bandwidth or storage space requirements, in some cases by two orders of magnitude or more. Both lossless and lossy compression, as well as a combination thereof can be employed. Lossless compression refers to techniques where an exact copy of the original signal can be reconstructed from the compressed original signal. When using lossy compression, the reconstructed signal may not be identical to the original signal, but the distortion between original and reconstructed signal is small enough to make the reconstructed signal useful for the intended application. In the case of video, lossy compression is widely employed. The amount of distortion tolerated depends on the application; for example, users of certain consumer streaming applications may tolerate higher distortion than users of television contribution applications. The compression ratio achievable can reflect that: higher allowable/tolerable distortion can yield higher compression ratios.
• a video encoder and decoder can utilize techniques from several broad categories, including, for example, motion compensation, transform, quantization, and entropy coding, some of which will be introduced below.
• video encoders and decoders tended to operate on a given picture size that was, in most cases, defined and stayed constant for a coded video sequence (CVS), Group of Pictures (GOP), or a similar multi-picture timeframe.
• CVS coded video sequence
• GOP Group of Pictures
• MPEG-2 system designs are known to change the horizontal resolution (and, thereby, the picture size) dependent on factors such as activity of the scene, but only at I pictures, hence typically for a GOP.
• the resampling of reference pictures for use of different resolutions within a CVS is known, for example, from ITU-T Rec. H.263 Annex P.
• H.263 Annex Q allows the resampling of an individual macroblock by a factor of two (in each dimension), upward or downward. Again, the picture size remains the same.
• the size of a macroblock is fixed in H.263, and therefore does not need to be signaled.
• VVC Video Team document JVET-M0135-v1, Jan 9-19, 2019
• different candidate resolutions are suggested to be coded in the sequence parameter set and referred to by per-picture syntax elements in the picture parameter set.
• Embodiments relate to a method, system, and computer readable medium as set out in the apended claims.
• FIG. 1 illustrates a simplified block diagram of a communication system (100) according to an embodiment of the present disclosure.
• the system (100) may include at least two terminals (110-120) interconnected via a network (150).
• a first terminal (110) may code video data at a local location for transmission to the other terminal (120) via the network (150).
• the second terminal (120) may receive the coded video data of the other terminal from the network (150), decode the coded data and display the recovered video data.
• Unidirectional data transmission may be common in media serving applications and the like.
• FIG. 1 illustrates a second pair of terminals (130, 140) provided to support bidirectional transmission of coded video that may occur, for example, during videoconferencing.
• each terminal (130, 140) may code video data captured at a local location for transmission to the other terminal via the network (150).
• Each terminal (130, 140) also may receive the coded video data transmitted by the other terminal, may decode the coded data and may display the recovered video data at a local display device.
• the terminals (110-140) may be illustrated as servers, personal computers and smart phones but the principles of the present disclosure may be not so limited. Embodiments of the present disclosure find application with laptop computers, tablet computers, media players and/or dedicated video conferencing equipment.
• the network (150) represents any number of networks that convey coded video data among the terminals (110-140), including for example wireline and/or wireless communication networks.
• the communication network (150) may exchange data in circuit-switched and/or packet-switched channels.
• Representative networks include telecommunications networks, local area networks, wide area networks and/or the Internet. For the purposes of the present discussion, the architecture and topology of the network (150) may be immaterial to the operation of the present disclosure unless explained herein below.
• FIG. 2 illustrates, as an example for an application for the disclosed subject matter, the placement of a video encoder and decoder in a streaming environment.
• the disclosed subject matter can be equally applicable to other video enabled applications, including, for example, video conferencing, digital TV, storing of compressed video on digital media including CD, DVD, memory stick and the like, and so on.
• FIG. 3 may be a functional block diagram of a video decoder (210) according to an embodiment of the present invention.
• a buffer memory (315) may be coupled in between receiver (310) and entropy decoder / parser (320) ("parser” henceforth).
• the buffer (315) may not be needed, or can be small.
• the buffer (315) may be required, can be comparatively large and can advantageously of adaptive size.
• the coding of the coded video sequence can be in accordance with a video coding technology or standard, and can follow principles well known to a person skilled in the art, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and so forth.
• the parser (320) may extract from the coded video sequence, a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder, based upon at least one parameters corresponding to the group. Subgroups can include Groups of Pictures (GOPs), pictures, tiles, slices, macroblocks, Coding Units (CUs), blocks, Transform Units (TUs), Prediction Units (PUs) and so forth.
• the entropy decoder / parser may also extract from the coded video sequence information such as transform coefficients, quantizer parameter values, motion vectors, and so forth.
• the parser (320) may perform entropy decoding / parsing operation on the video sequence received from the buffer (315), so to create symbols (321).
• Reconstruction of the symbols (321) can involve multiple different units depending on the type of the coded video picture or parts thereof (such as: inter and intra picture, inter and intra block), and other factors. Which units are involved, and how, can be controlled by the subgroup control information that was parsed from the coded video sequence by the parser (320). The flow of such subgroup control information between the parser (320) and the multiple units below is not depicted for clarity.
• a first unit is the scaler / inverse transform unit (351).
• the scaler / inverse transform unit (351) receives quantized transform coefficient as well as control information, including which transform to use, block size, quantization factor, quantization scaling matrices, etc. as symbol(s) (321) from the parser (320). It can output blocks comprising sample values, that can be input into aggregator (355).
• the output samples of the scaler / inverse transform (351) can pertain to an intra coded block; that is: a block that is not using predictive information from previously reconstructed pictures, but can use predictive information from previously reconstructed parts of the current picture.
• Such predictive information can be provided by an intra picture prediction unit (352).
• the intra picture prediction unit (352) generates a block of the same size and shape of the block under reconstruction, using surrounding already reconstructed information fetched from the current (partly reconstructed) picture (356).
• the aggregator (355) adds, on a per sample basis, the prediction information the intra prediction unit (352) has generated to the output sample information as provided by the scaler / inverse transform unit (351).
• the output samples of the scaler / inverse transform unit (351) can pertain to an inter coded, and potentially motion compensated block.
• a Motion Compensation Prediction unit (353) can access reference picture memory (357) to fetch samples used for prediction. After motion compensating the fetched samples in accordance with the symbols (321) pertaining to the block, these samples can be added by the aggregator (355) to the output of the scaler / inverse transform unit (in this case called the residual samples or residual signal) so to generate output sample information.
• the addresses within the reference picture memory form where the motion compensation unit fetches prediction samples can be controlled by motion vectors, available to the motion compensation unit in the form of symbols (321) that can have, for example X, Y, and reference picture components.
• Motion compensation also can include interpolation of sample values as fetched from the reference picture memory when sub-sample exact motion vectors are in use, motion vector prediction mechanisms, and so forth.
• Video compression technologies can include in-loop filter technologies that are controlled by parameters included in the coded video bitstream and made available to the loop filter unit (356) as symbols (321) from the parser (320), but can also be responsive to meta-information obtained during the decoding of previous (in decoding order) parts of the coded picture or coded video sequence, as well as responsive to previously reconstructed and loop-filtered sample values.
• the output of the loop filter unit (356) can be a sample stream that can be output to the render device (212) as well as stored in the reference picture memory (356) for use in future inter-picture prediction.
• coded pictures once fully reconstructed, can be used as reference pictures for future prediction.
• the current reference picture 356 can become part of the reference picture buffer (357), and a fresh current picture memory can be reallocated before commencing the reconstruction of the following coded picture.
• the video decoder 320 may perform decoding operations according to a predetermined video compression technology that may be documented in a standard, such as ITU-T Rec. H.265.
• the coded video sequence may conform to a syntax specified by the video compression technology or standard being used, in the sense that it adheres to the syntax of the video compression technology or standard, as specified in the video compression technology document or standard and specifically in the profiles document therein. Also necessary for compliance can be that the complexity of the coded video sequence is within bounds as defined by the level of the video compression technology or standard. In some cases, levels restrict the maximum picture size, maximum frame rate, maximum reconstruction sample rate (measured in, for example megasamples per second), maximum reference picture size, and so on. Limits set by levels can, in some cases, be further restricted through Hypothetical Reference Decoder (HRD) specifications and metadata for HRD buffer management signaled in the coded video sequence.
• HRD Hypothetical Reference Decoder
• the receiver (310) may receive additional (redundant) data with the encoded video.
• the additional data may be included as part of the coded video sequence(s).
• the additional data may be used by the video decoder (320) to properly decode the data and/or to more accurately reconstruct the original video data.
• Additional data can be in the form of, for example, temporal, spatial, or SNR enhancement layers, redundant slices, redundant pictures, forward error correction codes, and so on.
• FIG. 4 may be a functional block diagram of a video encoder (203) according to an embodiment of the present disclosure.
• the encoder (203) may receive video samples from a video source (201) (that is not part of the encoder) that may capture video image(s) to be coded by the encoder (203).
• the video source (201) may provide the source video sequence to be coded by the encoder (203) in the form of a digital video sample stream that can be of any suitable bit depth (for example: 8 bit, 10 bit, 12 bit, ...), any colorspace (for example, BT.601 Y CrCB, RGB, ...) and any suitable sampling structure (for example Y CrCb 4:2:0, Y CrCb 4:4:4).
• the video source (201) may be a storage device storing previously prepared video.
• the video source (203) may be a camera that captures local image information as a video sequence.
• Video data may be provided as a plurality of individual pictures that impart motion when viewed in sequence. The pictures themselves may be organized as a spatial array of pixels, wherein each pixel can comprise one or more sample depending on the sampling structure, color space, etc. in use.
• a person skilled in the art can readily understand the relationship between pixels and samples. The description below focusses on samples.
• the encoder (203) may code and compress the pictures of the source video sequence into a coded video sequence (443) in real time or under any other time constraints as required by the application. Enforcing appropriate coding speed is one function of Controller (450). Controller controls other functional units as described below and is functionally coupled to these units. The coupling is not depicted for clarity. Parameters set by controller can include rate control related parameters (picture skip, quantizer, lambda value of rate-distortion optimization techniques, ...), picture size, group of pictures (GOP) layout, maximum motion vector search range, and so forth. A person skilled in the art can readily identify other functions of controller (450) as they may pertain to video encoder (203) optimized for a certain system design.
• a coding loop can consist of the encoding part of an encoder (430) ("source coder” henceforth) (responsible for creating symbols based on an input picture to be coded, and a reference picture(s)), and a (local) decoder (433) embedded in the encoder (203) that reconstructs the symbols to create the sample data a (remote) decoder also would create (as any compression between symbols and coded video bitstream is lossless in the video compression technologies considered in the disclosed subject matter). That reconstructed sample stream is input to the reference picture memory (434).
• the reference picture buffer content is also bit exact between local encoder and remote encoder.
• the prediction part of an encoder "sees” as reference picture samples exactly the same sample values as a decoder would "see” when using prediction during decoding.
• This fundamental principle of reference picture synchronicity (and resulting drift, if synchronicity cannot be maintained, for example because of channel errors) is well known to a person skilled in the art.
• the operation of the "local" decoder (433) can be the same as of a “remote” decoder (210), which has already been described in detail above in conjunction with Fig. 3 .
• the entropy decoding parts of decoder (210), including channel (312), receiver (310), buffer (315), and parser (320) may not be fully implemented in local decoder (433).
• An Intra Picture may be one that may be coded and decoded without using any other frame in the sequence as a source of prediction.
• Some video codecs allow for different types of Intra pictures, including, for example Independent Decoder Refresh Pictures.
• I picture may be one that may be coded and decoded without using any other frame in the sequence as a source of prediction.
• Some video codecs allow for different types of Intra pictures, including, for example Independent Decoder Refresh Pictures.
• a Predictive picture may be one that may be coded and decoded using intra prediction or inter prediction using at most one motion vector and reference index to predict the sample values of each block.
• a Bi-directionally Predictive Picture may be one that may be coded and decoded using intra prediction or inter prediction using at most two motion vectors and reference indices to predict the sample values of each block.
• multiple-predictive pictures can use more than two reference pictures and associated metadata for the reconstruction of a single block.
• the video coder (203) may perform coding operations according to a predetermined video coding technology or standard, such as ITU-T Rec. H.265. In its operation, the video coder (203) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence.
• the coded video data therefore, may conform to a syntax specified by the video coding technology or standard being used.
• Sub-Picture henceforth refers to an, in some cases, rectangular arrangement of samples, blocks, macroblocks, coding units, or similar entities that are semantically grouped, and that may be independently coded in changed resolution.
• One or more sub-pictures may for a picture.
• One or more coded sub-pictures may form a coded picture.
• One or more sub-pictures may be assembled into a picture, and one or more sub pictures may be extracted from a picture.
• one or more coded sub-pictures may be assembled in the compressed domain without transcoding to the sample level into a coded picture, and in the same or certain other cases, one or more coded sub-pictures may be extracted from a coded picture in the compressed domain.
• Adaptive Resolution Change henceforth refers to mechanisms that allow the change of resolution of a picture or sub-picture within a coded video sequence, by the means of, for example, reference picture resampling.
• ARC parameters henceforth refer to the control information required to perform adaptive resolution change, that may include, for example, filter parameters, scaling factors, resolutions of output and/or reference pictures, various control flags, and so forth.
• Fig. 5 shown are several novel options for signaling ARC parameters. As noted with each of the options, they have certain advantages and certain disadvantages from a coding efficiency, complexity, and architecture viewpoint.
• a video coding standard or technology may choose one or more of these options, or options known from previous art, for signaling ARC parameters.
• the options may not be mutually exclusive, and conceivably may be interchanged based on application needs, standards technology involved, or encoder's choice.
• Classes of ARC parameters may include:
• the description assumes the coding of a finite set of up/downsample factors (the same factor to be used in both X and Y dimension), indicated through a codeword.
• That codeword can advantageously be variable length coded, for example using the Ext-Golomb code common for certain syntax elements in video coding specifications such as H.264 and H.265.
• One suitable mapping of values to up/downsample factors can, for example, be according to the following table Codeword Ext-Golomb Code Original / Target resolution 0 1 1/1 1 010 1 / 1.5 (upscale by 50%) 2 011 1.5 / 1 (downscale by 50%) 3 00100 1 / 2 (upscale by 100%) 4 00101 2 / 1 (downscale by 100%)
• mappings could be devised according to the needs of an application and the capabilities of the up and downscale mechanisms available in a video compression technology or standard.
• the table could be extended to more values. Values may also be represented by entropy coding mechanisms other than Ext-Golomb codes, for example using binary coding. That may have certain advantages when the resampling factors were of interest outside the video processing engines (encoder and decoder foremost) themselves, for example by MANEs. It should be noted that, for the (presumably) most common case where no resolution change is required, an Ext-Golomb code can be chosen that is short; in the table above, only a single bit. That can have a coding efficiency advantage over using binary codes for the most common case.
• the number of entries in the table, as well as their semantics may be fully or partially configurable.
• the basic outline of the table may be conveyed in a "high" parameter set such as a sequence or decoder parameter set.
• one or more such tables may be defined in a video coding technology or standard, and may be selected through for example a decoder or sequence parameter set.
• an upsample/downsample factor (ARC information), coded as described above, may be included in a video coding technology or standard syntax. Similar considerations may apply to one, or a few, codewords controlling up/downsample filters. See below for a discussion when comparatively large amounts of data are required for a filter or other data structures.
• H.263 Annex P includes the ARC information 502 in the form of four warping coordinates into the picture header 501, specifically in the H.263 PLUSPTYPE (503) header extension. This can be a sensible design choice when a) there is a picture header available, and b) frequent changes of the ARC information are expected. However, the overhead when using H.263-style signaling can be quite high, and scaling factors may not pertain among picture boundaries as picture header can be of transient nature.
• JVCET-M135-v1 includes the ARC reference information (505) (an index) located in a picture parameter set (504), indexing a table (506) including target resolutions that in turn is located inside a sequence parameter set (507).
• the placement of the possible resolution in a table (506) in the sequence parameter set (507) can, according to verbal statements made by the authors, be justified by using the SPS as an interoperability negotiation point during capability exchange. Resolution can change, within the limits set by the values in the table (506) from picture to picture by referencing the appropriate picture parameter set (504).
• Fig. 5 the following additional options may exist to convey ARC information in a video bitstream.
• Each of those options has certain advantages over existing art as described above.
• the options may be simultaneously present in the same video coding technology or standard.
• ARC information such as a resampling (zoom) factor may be present in a slice header, GOB header, tile header, or tile group header (tile group header henceforth) (508).
• This can be adequate of the ARC information is small, such as a single variable length ue(v) or fixed length codeword of a few bits, for example as shown above.
• Having the ARC information in a tile group header directly has the additional advantage of the ARC information may be applicable to a sub picture represented by, for example, that tile group, rather than the whole picture. See also below.
• the ARC information (512) itself may be present in an appropriate parameter set (511) such as, for example, a picture parameter set, header parameter set, tile parameter set, adapation parameter set, and so forth (Adapation parameter set depicted).
• an appropriate parameter set such as, for example, a picture parameter set, header parameter set, tile parameter set, adapation parameter set, and so forth (Adapation parameter set depicted).
• the scope of that parameter set can advantageously be no larger than a picture, for example a tile group.
• the use of the ARC information is implicit through the activation of the relevant parameter set. For example, when a video coding technology or standard contemplates only picture-based ARC, then a picture parameter set or equivalent may be appropriate.
• ARC reference information (513) may be present in a Tile Group header (514) or a similar data structure. That reference information (513) can refer to a subset of ARC information (515) available in a parameter set (516) with a scope beyond a single picture, for example a sequence parameter set, or decoder parameter set.
• ARC information is of more than negligible size-for example contains filter control information such as numerous filter coefficients-then a parameter may be a better choice than using a header (508) directly from a coding efficiency viewpoint, as those settings may be reusable by future pictures or sub-pictures by referencing the same parameter set.
• Fig. 6 depicts syntax diagrams in a representation as used in video coding standards since at least 1993. The notation of such syntax diagrams roughly follows C-style programming. Lines in boldface indicate syntax elements present in the bitstream, lines without boldface often indicate control flow or the setting of variables.
• a tile group header (601) as an exemplary syntax structure of a header applicable to a (possibly rectangular) part of a picture can conditionally contain, a variable length, Exp-Golomb coded syntax element dec_pic_size_idx (602) (depicted in boldface).
• dec_pic_size_idx 602 (depicted in boldface).
• the presence of this syntax element in the tile group header can be gated on the use of adaptive resolution (603)-here, the value of a flag not depicted in boldface, which means that flag is present in the bitstream at the point where it occurs in the syntax diagram.
• adaptive resolution 603-here, the value of a flag not depicted in boldface, which means that flag is present in the bitstream at the point where it occurs in the syntax diagram.
• adaptive resolution 603-here, the value of a flag not depicted in boldface, which means that flag is present in the bitstream at the point where it occurs in the syntax diagram.
• adaptive resolution
• FIG. 6 shown is also an excerpt of a sequence parameter set (610).
• the first syntax element shown is adaptive_pic_resolution_change_flag (611).
• that flag can indicate the use of adaptive resolution which, in turn may require certain control information.
• control information is conditionally present based on the value of the flag based on the if() statement in the parameter set (612) and the tile group header (601).
• coded is an output resolution in units of samples (613).
• the numeral 613 refers to both output_pic_width_in_luma_samples and output_pic_height_in_luma_samples, which together can define the resolution of the output picture.
• certain restrictions to either value can be defined. For example, a level definition may limit the number of total output samples, which could be the product of the value of those two syntax elements.
• certain video coding technologies or standards, or external technologies or standards such as, for example, system standards, may limit the numbering range (for example, one or both dimensions must be divisible by a power of 2 number), or the aspect ratio (for example, the width and height must be in a relation such as 4:3 or 16:9).
• the numbering range for example, one or both dimensions must be divisible by a power of 2 number
• the aspect ratio for example, the width and height must be in a relation such as 4:3 or 16:9.
• Such restrictions may be introduced to facilitate hardware implementations or for other reasons, and are well known in the art.
• Certain video coding technologies or standards support spatial scalability by implementing certain forms of reference picture resampling (signaled quite differently from the disclosed subject matter) in conjunction with temporal scalability, so to enable spatial scalability.
• certain reference pictures may be upsampled using ARC-style technologies to a higher resolution to form the base of a spatial enhancement layer. Those upsampled pictures could be refined, using normal prediction mechanisms at the high resolution, so to add detail.
• FIG. 7 shows a computer system 700 suitable for implementing certain embodiments of the disclosed subject matter.
• FIG. 8 shows an example of a video sequence structure with combination of temporal_id, layer_id, POC and AUC values with adaptive resolution change.
• the value of POC is increased by 1 per picture regardless of the values of temporal_id and layer_id.
• the value of poc_cycle_au can be equal to 2.
• the value of poc_cycle_au may be set equal to the number of (spatial scalability) layers. In this example, hence, the value of POC is increased by 2, while the value of AUC is increased by 1.
• all or sub-set of inter-picture or inter-layer prediction structure and reference picture indication may be supported by using the existing reference picture set (RPS) signaling in HEVC or the reference picture list (RPL) signaling.
• RPS or RPL the selected reference picture is indicated by signaling the value of POC or the delta value of POC between the current picture and the selected reference picture.
• the RPS and RPL can be used to indicate the inter-picture or inter-layer prediction structure without change of signaling, but with the following restrictions. If the value of temporal_id of a reference picture is greater than the value of temporal_id current picture, the current picture may not use the reference picture for motion compensation or other predictions. If the value of layer_id of a reference picture is greater than the value of layer_id current picture, the current picture may not use the reference picture for motion compensation or other predictions.
• the motion vector scaling based on POC difference for temporal motion vector prediction may be disabled across multiple pictures within an access unit.
• each picture may have a different POC value within an access unit
• the motion vector is not scaled and used for temporal motion vector prediction within an access unit. This is because a reference picture with a different POC in the same AU is considered a reference picture having the same time instance. Therefore, in the embodiment, the motion vector scaling function may return 1, when the reference picture belongs to the AU associated with the current picture.
• the reference motion vector in the same AU (with the same AUC value) with the current picture is not scaled based on AUC difference and used for motion vector prediction without scaling or with scaling based on spatial resolution ratio between the current picture and the reference picture.
• a coded sub-picture may be contained in one or more layers.
• a coded sub-picture in a layer may have a different spatial resolution.
• the original sub-picture may be spatially re-sampled (up-sampled or down-sampled), coded with different spatial resolution parameters, and contained in a bitstream corresponding to a layer.
• a coded sub-picture in a layer may have a different visual quality from that of the coded sub-picture in another layer in the same sub-picture or different subpicture.
• sub-picture i in a layer, n is coded with the quantization parameter, Q i,n
• a sub-picture j in a layer, m is coded with the quantization parameter, Q j,m .
• a coded sub-picture in a layer may be dependently decodable, with any parsing or decoding dependency from a coded sub-picture in another layer of the same local region.
• the sub-picture layer which can be dependently decodable with referencing another sub-picture layer of the same local region, is the dependent sub-picture layer.
• a coded sub-picture in the dependent sub-picture may reference a coded sub-picture belonging to the same sub-picture, a previously coded sub-picture in the same sub-picture layer, or both reference sub-pictures.
• a coded sub-picture consists of one or more independent sub-picture layers and one or more dependent sub-picture layers.
• at least one independent sub-picture layer may be present for a coded sub-picture.
• the independent sub-picture layer may have the value of the layer identifier (layer_id), which may be present in NAL unit header or another high-level syntax structure, equal to 0.
• layer_id layer identifier
• the sub-picture layer with the layer_id equal to 0 is the base sub-picture layer.
• a picture may consist of one or more foreground sub-pictures and one background sub-picture.
• the region supported by a background sub-picture may be equal to the region of the picture.
• the region supported by a foreground sub-picture may be overlapped with the region supported by a background sub-picture.
• the background sub-picture may be a base sub-picture layer, while the foreground sub-picture may be a non-base (enhancement) sub-picture layer.
• One or more non-base sub-picture layer may reference the same base layer for decoding.
• Each non-base sub-picture layer with layer_id equal to a may reference a non-base sub-picture layer with layer_id equal to b, where a is greater than b.
• a picture may consist of one or more foreground sub-pictures with or without a background sub-picture.
• Each sub-picture may have its own base sub-picture layer and one or more non-base (enhancement) layers.
• Each base sub-picture layer may be referenced by one or more non-base sub-picture layers.
• Each non-base sub-picture layer with layer_id equal to a may reference a non-base sub-picture layer with layer_id equal to b, where a is greater than b .
• a picture may consist of one or more foreground sub-pictures with or without a background sub-picture.
• Each coded sub-picture in a (base or non-base) sub-picture layer may be referenced by one or more non-base layer sub-pictures belonging to the same sub-picture and one or more non-base layer sub-pictures, which are not belonging to the same sub-picture.
• a picture may consist of one or more foreground sub-pictures with or without a background sub-picture.
• a sub-picture in a layer a may be further partitioned into multiple sub-pictures in the same layer.
• One or more coded sub-pictures in a layer b may reference the partitioned sub-picture in a layer a.
• a coded video sequence may be a group of the coded pictures.
• the CVS may consist of one or more coded sub-picture sequences (CSPS), where the CSPS may be a group of coded sub-pictures covering the same local region of the picture.
• CSPS coded sub-picture sequences
• a CSPS may have the same or a different temporal resolution than that of the coded video sequence.
• a CSPS may be coded and contained in one or more layers.
• a CSPS may consist of one or more CSPS layers. Decoding one or more CSPS layers corresponding to a CSPS may reconstruct a sequence of sub-pictures corresponding to the same local region.
• the number of CSPS layers corresponding to a CSPS may be identical to or different from the number of CSPS layers corresponding to another CSPS.
• a CSPS layer may have a different temporal resolution (e.g. frame rate) from another CSPS layer.
• the original (uncompressed) sub-picture sequence may be temporally re-sampled (up-sampled or down-sampled), coded with different temporal resolution parameters, and contained in a bitstream corresponding to a layer.
• a sub-picture sequence with the frame rate, F may be coded and contained in the coded bitstream corresponding to layer 0, while the temporally up-sampled (or down-sampled) sub-picture sequence from the original sub-picture sequence, with F* S t,k , may be coded and contained in the coded bitstream corresponding to layer k, where S t,k indicates the temporal sampling ratio for layer k. If the value of S t,k is greater than 1, the temporal resampling process is equal to the frame rate up conversion. Whereas, if the value of S t,k is smaller than 1, the temporal resampling process is equal to the frame rate down conversion.
• a sub-picture with a CSPS layer a is reference by a sub-picture with a CSPS layer b for motion compensation or any inter-layer prediction
• the spatial resolution of the CSPS layer a is different from the spatial resolution of the CSPS layer b
• decoded pixels in the CSPS layer a are resampled and used for reference.
• the resampling process may need an up-sampling filtering or a down-sampling filtering.
• FIG. 9 shows an example of syntax tables to signal the syntax element of vps_poc_cycle_au in VPS (or SPS), which indicates the poc_cycle_au used for all picture/slices in a coded video sequence, and the syntax element of slice_poc_cycle_au, which indicates the poc_cycle_au of the current slice, in slice header. If the POC value increases uniformly per AU, vps_contant_poc_cycle_per_au in VPS is set equal to 1 and vps_poc_cycle_au is signaled in VPS.
• slice_poc_cycle_au is not explicitly signaled, and the value of AUC for each AU is calculated by dividing the value of POC by vps_poc_cycle_au. If the POC value does not increase uniformly per AU, vps_contant_poc_cycle_per_au in VPS is set equal to 0. In this case, vps_access_unit_cnt is not signaled, while slice_access_unit_cnt is signaled in slice header for each slice or picture. Each slice or picture may have a different value of slice_access_unit_cnt. The value of AUC for each AU is calculated by dividing the value of POC by slice_poc_cycle_au.
• FIG. 10 shows a block diagram illustrating the relevant work flow.
• the picture, slice, or tile corresponding to an AU with the same AUC value may be associated with the same decoding or output time instance.
• all or subset of pictures, slices or tiles associated with the same AU may be decoded in parallel, and may be outputted at the same time instance.
• the picture, slice, or tile corresponding to an AU with the same AUC value may be associated with the same composition/display time instance.
• the composition time is contained in a container format, even though pictures correspond to different AUs, if the pictures have the same composition time, the pictures can be displayed at the same time instance.
• each picture, slice, or tile may have the same temporal identifier (temporal_id) in the same AU. All or subset of pictures, slices or tiles corresponding to a time instance may be associated with the same temporal sub-layer. In the same or other embodiments, each picture, slice, or tile may have the same or a different spatial layer id (layer _id) in the same AU. All or subset of pictures, slices or tiles corresponding to a time instance may be associated with the same or a different spatial layer.
• FIG. 11 shows an example video stream including a background video CSPS with layer_id equal to 0 and multiple foreground CSPS layers.
• a coded sub-picture may consist of one or more CSPS layers
• a background region which does not belong to any foreground CSPS layer, may consist of a base layer.
• the base layer may contain a background region and foreground regions
• an enhancement CSPS layer contain a foreground region.
• An enhancement CSPS layer may have a better visual quality than the base layer, at the same region.
• the enhancement CSPS layer may reference the reconstructed pixels and the motion vectors of the base layer, corresponding to the same region.
• the video bitstream corresponding to a base layer is contained in a track, while the CSPS layers corresponding to each sub-picture are contained in a separated track, in a video file.
• the video bitstream corresponding to a base layer is contained in a track, while CSPS layers with the same layer_id are contained in a separated track.
• a track corresponding to a layer k includes CSPS layers corresponding to the layer k , only.
• FIG. 12 shows an example of video conference based on the multi-layered sub-picture method.
• a video stream one base layer video bitstream corresponding to the background picture and one or more enhancement layer video bitstreams corresponding to foreground sub-pictures are contained.
• Each enhancement layer vide bitstream is corresponding to a CSPS layer.
• the picture corresponding to the base layer is displayed by default. It contains one or more user's picture in a picture (PIP).
• PIP picture
• FIG. 13 shows the diagram for the operation.
• each sub-region may be coded as an independent layer.
• Each independent layer corresponding to a local region may have a unique layer_id value.
• the sub-picture size and location information may be signaled. For example, picture size (width, height), the offset information of the left-top corner (x_offset, y_offset).
• FIG. 15 shows an example of the layout of divided sub-pictures, its sub-picture size and position information and its corresponding picture prediction structure.
• the layout information including the sub-picture size(s) and the sub-picture position(s) may be signaled in a high-level syntax structure, such as parameter set(s), header of slice or tile group, or SEI message.
• each sub-picture corresponding to an independent layer may have its unique POC value within an AU.
• the POC value(s) of each sub-picture corresponding to a layer may be used.
• vps_full_pic_width_in_luma_samples and vps_full_pic_height_in_luma_samples may be equal to the width and height of the input picture(s), respectively.
• vps_full_pic_width_in_luma_samples and vps _full_pic_height_in _luma_samples may not be used for decoding, but may be used for composition and display.
• the syntax elements pic_offset_x and pic_offset_y may be signaled in SPS, which corresponds to (a) specific layer(s).
• the coded picture size (pic_width_in_luma_samples, pic_height_in_luma_samples) signaled in SPS may be equal to the width and height of the sub-region corresponding to a specific layer.
• the position (pic_offset_x, pic_offset_y) of the left-top corner of the sub-region may be signaled in SPS.
• the layout information (size and position) of all or sub-set sub-region(s) of (an) input picture(s), the dependency information between layer(s) may be signaled in a parameter set or an SEI message.
• FIG. 18 shows an example of syntax elements to indicate the information o the layout of sub-regions, the dependency between layers, and the relation between a sub-region and one or more layers.
• the syntax element num_sub_region indicates the number of (rectangular) sub-regions in the current coded video sequence.
• the syntax element num_layers indicates the number of layers in the current coded video sequence. The value of num_layers may be equal to or greater than the value of num_subregion.
• the value of num_layers may be equal to the value of num_sub region.
• the value of num_layers may be greater than the value of num_subregion.
• the syntax element direct_dependency_flag[ i ][ j ] indicates the dependency from the j-th layer to the i-th layer.
• num_layers_for_region[ i ] indicates the number of layers associated with the i-th sub-region.
• sub_region_layer_id[ i ][ j ] indicates the layer_id of the j-th layer associated with the i-th sub-region.
• the sub_region_offset_x[ i ] and sub_region_offset_y[ i ] indicate the horizontal and vertical location of the left-top corner of the i-th sub-region, respectively.
• the sub_region_width [ i ] and sub_region_height[ i ] indicate the width and height of the i-th sub-region, respectively.
• one or more syntax elements that specify the output layer set to indicate one of more layers to be outputted with or without profile tier level information may be signaled in a high-level syntax structure, e.g. VPS, DPS, SPS, PPS, APS or SEI message.
• VPS high-level syntax structure
• the syntax element num_output_layer_sets indicating the number of output layer set (OLS) in the coded vide sequence referring to the VPS may be signaled in the VPS.
• output_layer_flag may be signaled as many as the number of output layers.
• output_layer_flag[ i ] 1 specifies that the i-th layer is output.
• vps_output_layer_flag[ i ] 0 specifies that the i-th layer is not output.
• one or more syntax elements that specify the profile tier level information for each output layer set may be signaled in a high-level syntax structure, e.g. VPS, DPS, SPS, PPS, APS or SEI message. Still referring to FIG. 19 , the syntax element num_profile_tile_level indicating the number of profile tier level information per OLS in the coded vide sequence referring to the VPS may be signaled in the VPS. For each output layer set, a set of syntax elements for profile tier level information or an index indicating a specific profile tier level information among entries in the profile tier level information may be signaled as many as the number of output layers.
• profile_tier_level_idx[ i ][ j ] specifies the index, into the list of profile_tier_level( ) syntax structures in the VPS, of the profile_tier_level( ) syntax structure that applies to the j-th layer of the i-th OLS.
• the syntax elements num_profile_tile_level and/or numoutput_layer_sets may be signaled when the number of maximum layers is greater than 1 (vps_max_minus1 > 0).
• the flag vps_ptl_signal_flag[ i ] may be present for the i-th output layer set.
• the profile tier level information for the i-th output layer set may or may not be signaled.
• Sublayer indicates a temporal scalable layer of a temporal scalable bitstream, consisting of VCL NAL units with a particular value of the TemporalId variable and the associated non-VCL NAL units.
• Sublayer representation indicates a subset of the bitstream consisting of NAL units of a particular sublayer and the lower sublayers.
• a VPS RBSP may be available to the decoding process prior to it being referenced, included in at least one AU with TemporalId equal to 0 or provided through external means. All VPS NAL units with a particular value of vps _video_parameter_set_id in a CVS may have the same content.
• vps_video_parameter_set_id provides an identifier for the VPS for reference by other syntax elements.
• the value of vps_video_parameter_set_id may be greater than 0.
• vps_all_layers_same_num_sublayers_flag 1 specifies that the number of temporal sublayers is the same for all the layers in each CVS referring to the VPS.
• vps_all_layers_same_num_sublayers_flag 0 specifies that the layers in each CVS referring to the VPS may or may not have the same number of temporal sublayers.
• the value of vps_all_layers_same_num_sublayers_flag is inferred to be equal to 1.
• the values of LayerUsedAsRefLayerFlag[ i ] and LayerUsedAsOutputLayerFlag[ i ] may not be both equal to 0. In other words, there may be no layer that is neither an output layer of at least one OLS nor a direct reference layer of any other layer.
• Each layer may be included in at least one OLS specified by the VPS.
• nuh_layer_id nuhLayerId equal to one of vps_layer_id[ k ] for k in the range of 0 to vps_max_layers_minus1, inclusive
• there may be at least one pair of values of i and j where i is in the range of 0 to TotalNumOlss - 1, inclusive, and j is in the range of NumLayersInOls[ i ] - 1, inclusive, such that the value of LayerIdInOls[ i ][ j ] is equal to nuhLayerId.
• PictureOutputFlag is set equal to 0 when sps_video_parameter_set_id is greater than 0, each_layer_is_an_ols_flag is equal to 0, ols_mode_idc is equal to 0 and the current AU contains a picture picA that satisfies all of the following conditions: PicA has PictureOutputFlag equal to 1, PicA has nuh_layer_id nuhLid greater than that of the current picture and PicA belongs to the output layer of the OLS (i.e., OutputLayerIdInOls[ TargetOlsIdx ][ 0 ] is equal to nuhLid).
• PictureOutputFlag is set equal to 0 when sps_video_parameter_set_id is greater than 0, each_layer_is_an_ols_flag is equal to 0, ols_mode_idc is equal to 2, and ols_output_layer_flag[ TargetOlsIdx ][ GeneralLayerIdx[ nuh _layer_id ] ] is equal to 0.
• a flag that indicates whether the current picture is referenced by the following pictures or not is signaled in a picture header or a slice header.
• non_reference_picture _flag is signaled in picture header.
• non_reference_picture _flag 1 specifies the picture associated with the PH is never used as a reference picture.
• non_reference_picture _flag 0 specifies the picture associated with the PH may or may not be used as a reference picture.
• a flag that indicates whether the current picture is cropped and outputted or not is signaled in a picture header or a slice header.
• the value of pic_output_flag may be equal to 1, because any picture, which is not referenced by the following pictures and not outputted, may not be included in the video bitstream, at decoder side.
• the pic_output_flag is not explicitly signaled, but inferred to be equal to 1.
• a non-referenced picture that is not outputted may not be encoded into a coded bitstream.
• a coded picture with non_reference_picture_flag is equal to 1 and pic_output_flag equal to 0 may be discarded from the coded bitstream.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Computing Systems (AREA)
• Theoretical Computer Science (AREA)
• Compression Or Coding Systems Of Tv Signals (AREA)
• Image Processing (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Related Child Applications (2)

Publications (4)

Family

ID=77921990

Family Applications (2)

Family Applications After (1)

Country Status (9)

Families Citing this family (2)

Family Cites Families (5)

• 2020
  • 2020-11-03 US US17/087,865 patent/US11722656B2/en active Active
• 2021
  • 2021-02-15 WO PCT/US2021/018099 patent/WO2021202000A1/en not_active Ceased
  • 2021-02-15 JP JP2021562365A patent/JP7551225B2/ja active Active
  • 2021-02-15 AU AU2021249201A patent/AU2021249201B2/en active Active
  • 2021-02-15 CN CN202180002864.5A patent/CN114270715B/zh active Active
  • 2021-02-15 CA CA3137815A patent/CA3137815A1/en active Pending
  • 2021-02-15 EP EP21781670.1A patent/EP3939168B1/en active Active
  • 2021-02-15 EP EP25191523.7A patent/EP4614978A3/en active Pending
  • 2021-02-15 KR KR1020257019106A patent/KR20250088789A/ko active Pending
  • 2021-02-15 KR KR1020217035680A patent/KR102820410B1/ko active Active
  • 2021-02-15 CN CN202411184900.6A patent/CN119135885A/zh active Pending
  • 2021-02-15 SG SG11202111749RA patent/SG11202111749RA/en unknown
• 2023
  • 2023-05-01 US US18/310,058 patent/US12095985B2/en active Active
  • 2023-05-23 AU AU2023203222A patent/AU2023203222B2/en active Active
  • 2023-07-20 JP JP2023118496A patent/JP7723044B2/ja active Active
• 2024
  • 2024-08-19 US US18/808,959 patent/US20240414322A1/en active Pending
• 2025
  • 2025-07-30 JP JP2025127647A patent/JP2025156439A/ja active Pending
  • 2025-08-08 AU AU2025213683A patent/AU2025213683A1/en active Pending

Also Published As

Similar Documents

Legal Events